# Making a hole in an existing object
**URL:** https://discourse.shapr3d.com/t/making-a-hole-in-an-existing-object/20999
**Category:** Modeling Questions
**Created:** [August 19, 2022, 9:32pm UTC](https://discourse.shapr3d.com/t/making-a-hole-in-an-existing-object/20999 "2022-08-19T21:32:59Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@onewheelskyward](https://discourse.shapr3d.com/u/onewheelskyward)
#### Post date: [August 19, 2022, 9:32pm UTC](https://discourse.shapr3d.com/t/making-a-hole-in-an-existing-object/20999/1 "2022-08-19T21:32:59Z")
Hey! I have an STL I downloaded, and there’s a flat surface, aligned with the ground that I’d like to make some holes in. I can draw the shapes, but because the object is floating above/below the surface, any extrusion just adds material rather than subtracting it.
I suppose my question could be, how do I force an extrusion to be negative space rather than positive? I hope I’m describing this correctly.
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### Author:  [@TigerMike](https://discourse.shapr3d.com/u/TigerMike)
#### Post date: [August 19, 2022, 10:55pm UTC](https://discourse.shapr3d.com/t/making-a-hole-in-an-existing-object/20999/2 "2022-08-19T22:55:08Z")
STL’s can be tricky to work with. Here, the orange body is an STL object. I extrude a cylinder thru the STL and then subtract it.
[https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/f/e/fedeb8c6369f442bc1dc2c19fde24a65c8fb714b.mov](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/f/e/fedeb8c6369f442bc1dc2c19fde24a65c8fb714b.mov)
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### Author:  [@onewheelskyward](https://discourse.shapr3d.com/u/onewheelskyward)
#### Post date: [August 20, 2022, 2:53pm UTC](https://discourse.shapr3d.com/t/making-a-hole-in-an-existing-object/20999/3 "2022-08-20T14:53:08Z")
Thanks TigerMike! I played around some more yesterday after posting, and that’s the same solution I came up with. It got me where I wanted to go.
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### Author:  [@TigerMike](https://discourse.shapr3d.com/u/TigerMike)
#### Post date: [August 20, 2022, 9:22pm UTC](https://discourse.shapr3d.com/t/making-a-hole-in-an-existing-object/20999/4 "2022-08-20T21:22:26Z")
Here’s another tidbit. Sometimes I make the STL semi-transparent (temporarily) so I can see how much I want to create a recess when I don’t want it all the way thru the part.
[https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/6/1/6124ab9afd6f940e9d054b1f54b4c0b71b15a228.mov](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/6/1/6124ab9afd6f940e9d054b1f54b4c0b71b15a228.mov)
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### Author:  [@five](https://discourse.shapr3d.com/u/five)
#### Post date: [August 18, 2023, 3:43pm UTC](https://discourse.shapr3d.com/t/making-a-hole-in-an-existing-object/20999/5 "2023-08-18T15:43:07Z")
How did you make the box transparent?
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### Author:  [@TigerMike](https://discourse.shapr3d.com/u/TigerMike)
#### Post date: [August 18, 2023, 4:55pm UTC](https://discourse.shapr3d.com/t/making-a-hole-in-an-existing-object/20999/6 "2023-08-18T16:55:14Z")
You have to select and go through Visualization. Not sure if it is available in the free version of Shapr3D.